<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin:0;
            padding: 0;
            list-style: none;

        }
        .tab {
            width: 600px;
            
            margin: 50px auto;
        }
        #title {
            display: flex;
        }

        #title>h2 {
            width: 198px;
            border: 1px solid#000;
            height: 40px;
            line-height: 40px;
            text-align: center;
            font-size: 24px;
            background-color:azure; 
        }

        #con>li {
            height: 400px;
            line-height: 400px;
            text-align: center;
            font-size: 40px;
            border: 1px solid#000;
            display: none;
        }
        
        #con>li.show {
            display: block;
        }
    </style>
</head>
<body>
    <div class="tab">
        <div id="title">
            <h2 class="active">标题一</h2>
            <h2>标题二</h2>
            <h2>标题三</h2>
        </div>
        <ul id="con">
            <li class="show">内容一</li>
            <li>内容二</li>
            <li>内容三</li>
        </ul>
    </div>
</body>
</html>